Are those tests random? If they aren’t, I would assume unsafe memory usage.
If this is happening on certain configurations, we saw something similar with Eigen and its initialization. If I remember correctly, on Mac, the default was Eigen set everything to 0, but in linux, it didn’t. That lead to failures when elements weren’t initialized to a value explicitly. (We fixed that with an Eigen typedef, but this is just what I tend to think about when there are random failures.)